UpAir One battery mod, maybe not!

Not too long ago I have written about my battery mod.
I have flown the mod 2 or 3 times, and the only successful one was the first ever flight.
Back then I was happy with the results, not knowing what I know now.

At an event in December I had 2 crashes in 10 minutes, both were with the battery mod.

At that time I thought that it was due to interference with all the other drones flying around there.
With the first crash there were over 10 drones airborne, so would be plausible.
The second time though, I was in the air, together with a racer. even then I thought it was the interference of the racer.
There was no damage done to the drone, apart from a lost gimbal rubber, nothing major.

2 weeks ago I went flying with my daughter, and have used the mod there as well.
This time there was no crash, but 2 sudden landings. The screen changed to LAND mode, and the drone wanted to land. I could overrule that, but the drone flew very bad as if there was no GPS lock, or a badly calibrated compass.
It was somewhat flyable in ALTHOLD mode, but reaction to controller inputs was very slow, are movement was sluggish.

Switched to the stock battery I took with me as well, and all problems were gone, just like that. flying it was great again, and POSHOLD was rock solid!

I have talked with some other UpAir pilots that have done the mod, and all of them had problems with flying behaviour. I even had a question via this site if there was a fix for a non responsive drone after the mod.

This completes my puzzle about my crash.
With my crash the drone tipped over as if 1 motor stopped shortly. It recovered from that, but entered a Vortex Ring State that I could not stop, resulting in a very hard landing.

Knowing all this know I dare to say that this mod is good for the extra flying time, but that is about it.
For some odd reason the drone reacts different to these batteries, making it do things it would normally not do.